The present invention generally relates to cutting methods and equipment. More particularly, this invention relates to an apparatus equipped with an impeller assembly that positions and orients elongate food products prior to encountering a cutting device that produces size-reduced products of generally consistent thickness.
Various types of equipment are known for slicing, shredding and granulating food products such as vegetables, fruits, and meat products. A particular example is slicing equipment adapted for cutting root vegetables such as potatoes into thin slices suitable for making potato chips (also known as potato crisps). A widely used machine for this purpose is commercially available from Urschel Laboratories, Inc., under the name Urschel Model CC®. The Model CC® is a centrifugal-type slicer capable of producing uniform slices, strip cuts, shreds and granulations of a wide variety of food products at high production capacities. When used to produce potato slices for potato chips, the Model CC® can make use of substantially round potatoes to produce the desired circular chip shape with a minimum amount of scrap. Descriptions pertaining to the construction and operation of the Model CC®, including improved embodiments thereof, are contained in U.S. Pat. Nos. 5,694,824 and 6,968,765, the entire contents of which are incorporated herein by reference.
FIGS. 1 and 3 are perspective views of an impeller 10 and cutting head 12, respectively, of types that can be used in the Model CC® machine. In operation, the impeller 10 is coaxially mounted within the cutting head 12, which is generally annular-shaped with cutting knives 14 mounted on its perimeter. The impeller 10 rotates within the cutting head 12, which remains stationary. Each knife 14 projects radially inward toward the impeller 10 and in a direction generally opposite the direction of rotation of the impeller 10, and defines a cutting edge at its radially innermost extremity. The impeller 10 has generally radially-oriented paddles 16 with faces 34 that engage and direct food products (e.g., potatoes) 36 radially outward against the knives 14 of the cutting head 12 as the impeller 10 rotates. The paddles 16 are shown as oriented to have what is termed herein a negative pitch, which as viewed in FIG. 2 denotes that the face 34 of each paddle 16 has a radially innermost extent angled away from the direction of rotation of the impeller 10 relative to a radial 38 of the impeller 10 terminating at the radially outermost extent of the face 34. Such an orientation has been found to be preferred with the impeller 10 and cutting head 12 of FIGS. 1 through 3. The impeller 10 is typically formed as a casting, such as from a manganese aluminum bronze (MAB) alloy, and therefore has a unitary construction.
The cutting head 12 shown in FIG. 3 comprises a lower support ring 18, an upper mounting ring 20, and circumferentially-spaced support segments 22. The knives 14 of the cutting head 12 are individually secured with clamping assemblies 26 to the support segments 22, which are pivotally attached to the support and mounting rings 18 and 20, such as with one or more coaxial pins (not shown) that engage holes in the support and/or mounting rings 18 and 20. By pivoting on the pins, the orientation of a support segment 22 can be adjusted to alter the radial location of the cutting edge of its knife 14 with respect to the axis of the cutting head 12, thereby controlling the thickness of the sliced food product. As an example, adjustment can be achieved with an adjusting screw and/or pin 24 located circumferentially behind the pivot pins. FIG. 3 further shows gate insert strips 23 mounted to each support segment 22 immediately downstream of each knife 14. The gate insert strips 23 do not cover the entire axial extent of the cutting head 12, but instead define an opening 25 at each of their lower ends through which rocks and other debris that settle by gravity toward the bottom of the impeller 10 can feed through the cutting head 12 without damaging the knives 14.
The knives 14 can be attached to their respective support segments with bolts, clamping assemblies, etc. FIGS. 9 and 10 are cross-sectional views through a portion of the cutting head 12 looking toward the lower support ring 18. FIG. 9 shows a knife 14 held in place with a clamping assembly 26 comprising inner and outer holders 27 and 28 secured with bolts 29 to a support segment 22, generally as described in U.S. Pat. No. 6,968,765 and particularly in reference to FIG. 7 of this prior patent. FIG. 10 shows a knife 14 encased in a plastic cartridge 30, which helps to protect the knife 14 from damage by rocks and other debris that may be embedded in or otherwise present with the food products being fed through the impeller 10. The knife 14 and its plastic cartridge 30 are held in place between a pair of holders 27 and 28, with the radially outer holder 28 being forcibly held in place on the support segment 22 with a clamping rod 32. The clamping rod 32 is shown oriented perpendicular to the support and mounting rings 18 and 20, and secured to the radially inner holder 27 with a fastener 31. Rotating a lever 33 creates a camming action that forces the outer holder 28 outward against the rod 32, and forcing the outer holder 28 against the knife 14. In each case, the knives 14 are disposable and must be replaced to maintain the cutting efficiency of the cutting head 12 and the quality of the sliced food product. The cutting edge 15 of each knife 14 is shown in FIGS. 9 and 10 as being formed to have a double bevel. As evident from FIG. 9, the trajectory 35 of slices produced at the knife edge 15 is free of any obstacles downstream and radially outward from a plane defined by the outer surface of the outer holder 28. In FIG. 10, the plastic cartridge 30 deflects slices away from the clamping rod 32.
While the Model CC® has performed extremely well for its intended purpose, further improvements are continuously desired and sought for slicing machines of the type represented by the Model CC®. For example, knives with double bevels as shown in FIGS. 9 and 10 tend to compress food product during slicing. In the case of slices cut from potatoes and cooked in oil to produce potato chips, compression during slicing can be sufficient to cause starch loss, which undesirably promotes oil absorption during cooking. While single-bevel knives reduce compression, they reduce the trajectory angle to the extent that the slices tend to impact the clamping rod 32 downstream. Though the plastic cartridge 30 avoids this by deflecting slices away from the clamping rod 32, the compressibility of the plastic material reduces the precision with which the cutting edges 15 of the knives 14 can be located, making production of slices with consistent thicknesses difficult. Other variables that can affect the operation of the Model CC® slicing machine and/or reduce the consistency of slices include the presence of contaminants such as stones embedded or mixed in with the products, which can damage the cutting edges of the knives, and the use of small products that tend to roll within the impeller 10.